The object of this study is to utilize biosynthetic methods to verify the structure of phaeomelanin, and at the same time illucidate the biosynthetic pathway between dihydroxyphenylalanine and this interesting polymeric red-brown pigment produced in human hair and skin. During the course of this study, radioactively labeled phaeomelanins will be produced. These will be of unestimable aid in unravelling the complexities of the photochemical reactions of phaeomelanin. The successful completion of this project will result in the synthesis of several new organic compounds which are either degradation products or putative intermediates along the biosynthetic path.